Optimax Engine Oil Reserve tank Filling in This Old Boat Posted June 9, 2020 So I ended up running my onboard tank low and the motor reserve tank started feeding the motor. Long story short the 4 beep alarm came on and wont go away until reserve the tank is full. I filled the large onboard tank however the reserve tank is not filling itself. It seems like the reserve tank needs to be bled? Does anyone know if you just loosen the cap and run the motor? I have stripped one of the caps before and that required a new tank ($$$). Anyone with any experience or advice I would be glad to hear from. Thanks!